Method of and apparatus for enhancing the shelf-stability of a biological product

Abstract: The shelf-stability of biological products is enhanced by subjecting the product to a pressure and decreasing the pressure rapidly so that cell walls of contaminating organisms are ruptured. The product may optionally be blanched or milled, decrease in pressure may be effected by passing the product through a homogenizing valve. A preferred product is carrot root material. The treated product is prevented from re-contamination.

Description: According to the invention there is provided a method of enhancing the shelf-stability of a biological product by subjecting it to a decreasing pressure, characterised in that the decreasing pressure is achieved by passing the product through a homogenising valve, such that the decreasing pressure is sufficiently rapid to cause rupturing of the cell walls of contaminating organisms in the product, and in that it includes thereafter keeping the product from re-contamination by such organisms. The pressure in the product may be decreased in the homogenising valve from at least about 400 bar down to atmospheric pressure. The cellular burst technique utilised (i.e. the rapid reduction in pressure), in addition to diminishing or destroying altogether the viability of the contaminating organisms in the product, also causes rupturing of the cell walls of the biological product itself, and this has the effect of inactivating or otherwise controlling certain biochemical and non-biochemical reactions that are supported by intact cells of the product and that cause quality degradation and other undesirable changes in the product. The product may be blanched prior to its being subjected to said rapidly decreasing pressure. The blanched product may be milled prior to its being subjected to said rapidly decreasing pressure. The product may be kept from re-contamination by a process selected from the group of processes consisting of: packaging the product under aseptic conditions in aseptic packaging; freezing the product and keeping it in a frozen condition; and drying the product and packaging the dried product in moisture impermeable packaging. The product may be a vegetable product, and more particularly a carotene rich vegetable product. The product may be carrot root material. Further according to the invention there is provided apparatus for enhancing the shelf-stability of a biological product, comprising treatment means for subjecting the product to a decreasing pressure, characterised in that the treatment means comprises a homogeniser including a homogenising valve through which the product can be passed, thereby subjecting the product to a decreasing pressure which is sufficiently rapid to cause rupturing of the cell walls of contaminating organisms in the product, to provide a treated product, and in that it further comprises post-treatment means for turning the treated product under aseptic conditions into a condition in which it is protected against re-contamination by contaminating organisms. The post-treatment means may be selected from the group consisting of: aseptic packaging apparatus for packaging the treated product in aseptic packaging; refrigeration apparatus for freezing the treated product; and drying apparatus for drying the treated product and packaging the dried product in moisture impermeable packaging. The apparatus may further comprise pre-treatment means upstream of the treatment means, the pre-treatment means including blanching means for blanching the product prior to its being subjected to said rapidly decreasing pressure. The pre-treatment means may further comprise a mill for milling the blanched product prior to its being subjected to said rapidly decreasing pressure. The invention will now be described in more detail, by way of example, with reference later to the accompanying drawing which is a block diagram of apparatus in accordance with the invention for enhancing the shelf-stability of a biological product. The following is an example of the method of the invention. EXAMPLE: Carrot ( daucus carota ) root material was cleaned, washed, and sliced to provide pieces of approximately 25mm x 25mm x 25mm in size. The material was then blanched in boiling water for 15 to 20 minutes for the purpose of softening the material, controlling the bacterial load, and inactivating enzyme systems that have a negative effect on the shelf-stability of the end product. At this stage the product should have a relatively large particle size so that, whilst heat penetration can take place, there is relatively little water penetration. This procedure has the effect of reducing biological activity in the end product, which may lead to undesirable gas generation. The material was then milled to comminute it further, and was thereafter subjected to a cell burst procedure. In the cell burst procedure the material was first de-aerated to remove as much air or other gases in the material as possible. It was then fed to the intake of a high pressure pump which increased the pressure in the material to up to 1000 bar. The material was released from the discharge of the pump back to essentially atmospheric pressure, the resultant sudden reduction in pressure causing the cell walls of the material and also of any microbial cells in the material to rupture. From the pump the material was conveyed under aseptic conditions to an aseptic packaging machine, where it was packaged in aseptic packaging. Turning now to the drawing, reference numeral 10 generally indicates apparatus for processing and packaging a biological product, and more particularly carrot root material. The apparatus comprises a dicer or slicer 12, a blanching device 14, a mill 16, and a homogenizer 18. The homogenizer 18 has a homogenizing valve 20 which feeds into an aseptic packaging machine 22. The aseptic packaging machine 22 forms part of a packaging line which includes a conveyor 24 whereby aseptic packaging sachets, bags, or other containers 26 are conveyed past the filler nozzle of the aseptic packaging machine. The region from the homogenizing valve 20 to the aseptic packaging machine 22, as indicated by the dotted line 28 is maintained in an aseptic condition. Homogenizing machines are known in the art. The homogenizing valve in these machines usually comprises a spring-loaded ball element which seats on a valve seat. When product is forced through the valve the pressure unseats the ball element and the product squeezed through the narrow annular gap that forms between the ball element and the valve seat as the ball element is unseated. In addition to the rapid decrease in pressure which the product undergoes when passing through the valve, the surfaces of the valve where the product passes through the annular gap have a shearing effect on the cells of the product and of contaminating organisms in the product. This is believed to assist in rupturing the cell walls of the product and any contaminating organisms in the product.

Claims: A method of enhancing the shelf-stability of a biological product by subjecting it to a decreasing pressure, characterised in that the decreasing pressure is achieved by passing the product through a homogenising valve (20), such that the decreasing pressure is sufficiently rapid to cause rupturing of the cell walls of contaminating organisms in the product, and in that it includes thereafter keeping the product from re-contamination by such organisms. A method as claimed in claim 1, characterised in that the pressure in the product is decreased in the homogenising valve from at least 400 bar down to atmospheric pressure. A method as claimed in claim 1 or claim 2, characterised in that the product is blanched prior to its being subjected to said rapidly decreasing pressure. A method as claimed in claim 3, characterised in that the blanched product is milled prior to its being subjected to said rapidly decreasing pressure. A method as claimed in any one of the preceding claims, characterised in that the product is kept from re-contaminating by a process selected from the group of processes consisting of: packaging the product under aseptic conditions in aseptic packaging; freezing the product and keeping it in a frozen condition; and drying the product and packaging the dried product in moisture impermeable packaging. A method as claimed in any one of claims 1 to 4, characterised in that the product is kept from re-contamination by packaging it under aseptic conditions in aseptic packaging. A method as claimed in any one of the preceding claims, characterised in that the product is a vegetable product. A method as claimed in claim 7, characterised in that the product is a carotene rich vegetable product. A method as claimed in claim 7, characterised in that the product is carrot root material. Apparatus for enhancing the shelf-stability of a biological product, comprising treatment means for subjecting the product to a decreasing pressure, characterised in that the treatment means comprises a homogeniser (18) including a homogenising valve (20) through which the product can be passed, thereby subjecting the product to a decreasing pressure which is sufficiently rapid to cause rupturing of the cell walls of contaminating organisms in the product, to provide a treated product, and in that it further comprises post-treatment means (22, 24, 26, 28) for turning the treated product under aseptic conditions into a condition in which it is protected against re-contamination by contaminating organisms. Apparatus as claimed in claim 10, characterised in that the post-treatment means is selected from the group consisting of: aseptic packaging apparatus (22) for packaging the treated product in aseptic packaging (26); refrigeration apparatus for freezing the treated product; and drying apparatus for drying the treated product and packaging the dried product in moisture impermeable packaging. Apparatus as claimed in claim 10, characterised in that the post-treatment means is in the form of aseptic packaging apparatus (22) for packaging the treated product in aseptic packaging (26). Apparatus as claimed in any one of claims 10 to 12, characterised in that it further comprises pre-treatment means (14, 16) upstream of the treatment means, the pre-treatment means including blanching means (14) for blanching the product prior to its being subjected to said rapidly decreasing pressure. Apparatus as claimed in claim 13, characterised in that the pre-treatment means comprises a mill (16) for milling the blanched product prior to its being subject to said rapidly decreasing pressure.

Inventors: VAN NOORT GERARD, VAN NOORT, GERARD
Applicants: NOORT GERARD VAN, VAN NOORT, GERARD
Application year: 1994
Main classification: A23L3
IPC codes: A23B7, A23L3